New (to me) Amplifier...

[timbo]

Just made a deal on a Kenwood TL-922a legal limit amp. It's going to need a bit of TLC, mostly cosmetic stuff, but the guy that owned it said it works fine, no arcs inside and it's power tubes are good. It uses two 3-500's. Even if they are soft, I have a brand new pair I bought years ago, thinking I was going to homebrew a two holer 3-500 amp. These amps are selling on the 'bay for anywhere between $1K-2K, depending on age, what brand tubes it has and condition of the amp.

This one I'm picked up was a steal. The amp weighs in at 75 pounds so shipping from the left coast isn't exactly cheap but even with the cost of shipping it in two boxes (the tubes are packed and shipped separately), it was still half of the low price on eBay.

I'll have to do some "upgrades" to the circuitry that really needs to be done for the amp to run better. I'll also install a few protective circuits to keep the fireworks out of the amp should something going awry.

And...this will force me to run 240 volts out to my shack, something I've been putting off since 2011 when the house was built. I'll be installing a 240v 60 amp sub-panel in the garage in the next month or so.

It'll be nice to have a bit of extra push on my signal when needed. Conditions have been utterly terrible the past few weeks...those DX stations I can hear are not hearing my piss weak little station.

A little blurb on the amp:

Kenwood TL922A Amplifier. Kenwood TL-922A amp

www.universal-radio.com

 

[Uzi2]

Use resonant antenni and you're unlikely to see any arching anywhere.

Hopefully the tubes arrive in working order......and even more hopefully they are insured in shipment.

A set of 3-500z tubes should last a lifetime if properly cared for.

 

[UJay]

Congrats @timbo - That is a fine piece of equipment. We used to have one at the multiop contest station and we would beat the crap out of it for > 48 hours. I remember there was a plastic coffee mug that melted to the top at some point...

I think we had problems with the bandswitch a couple of times. I will have to ask the guys and the current owner-

240vac for sure. makes a world of difference-

Congrats again-

uj

 

[timbo]

Use resonant antenni and you're unlikely to see any arching anywhere.

Hopefully the tubes arrive in working order......and even more hopefully they are insured in shipment.

A set of 3-500z tubes should last a lifetime if properly cared for.

I'm using a Dentron MT-2000 tuner to feed my 265' ladderline fed Zepp. I had a TL-922a many years ago so I'm familiar with all their foibles. When I did tech work at HRO back in the 90's, I saw alot of zorched amps come through the shop but very rarely did I see 922's except for when they wanted me to install the 10 meter mod. I think I only saw one come through the shop with an arced bandswitch. Replacing it was tedious but not hard. It's mostly parasitics that will get you. The parasitic suppressors they used didn't do as good of a job as they should've but there are better ways of doing it now.

The shipper is insuring the tubes for $600 and the amp for $1500.

 

[timbo]

Congrats @timbo - That is a fine piece of equipment. We used to have one at the multiop contest station and we would beat the crap out of it for > 48 hours. I remember there was a plastic coffee mug that melted to the top at some point...

I think we had problems with the bandswitch a couple of times. I will have to ask the guys and the current owner-

240vac for sure. makes a world of difference-

Congrats again-

uj

Yep on the bandswitch. Most of the times that a BS is zorched is when the amp is being run by someone that isn't paying attention to what they're doing. I had one for about 8 years and never had a problem...you just have to be careful. Fortunately, there is a company that makes after market switches that are actually way better than the original, to the tune of about $190. I'm considering buying one to have a spare, just in case...

I'm definitely going to go through the amp when I get it and make a few "ECO"s to it

 

[drgrant]

TL922As are a dumpster fire but if you do all the stuff Rich Measures talked about, they can be made into decent amplifiers.

-Mike

 

[timbo]

TL922As are a dumpster fire but if you do all the stuff Rich Measures talked about, they can be made into decent amplifiers.

-Mike

I wouldn't go so far as to call it a dumpster fire...all in all, it was a very ruggedly built legal limit amp for its size and price point. It is a fairly old design (80's vintage) but like you said, perform a few of AG6K's updates and a couple of W8JI's mods and you'll be good to go. Definitely not a Henry but then, the 922 was about 50% of the price of a Henry too.

Furthermore, it'll help heat the shack during the cooler nights. Real radios glow in the dark

 

[Silverado]

Just made a deal on a Kenwood TL-922a legal limit amp. It's going to need a bit of TLC, mostly cosmetic stuff, but the guy that owned it said it works fine, no arcs inside and it's power tubes are good. It uses two 3-500's. Even if they are soft, I have a brand new pair I bought years ago, thinking I was going to homebrew a two holer 3-500 amp. These amps are selling on the 'bay for anywhere between $1K-2K, depending on age, what brand tubes it has and condition of the amp.

This one I'm picked up was a steal. The amp weighs in at 75 pounds so shipping from the left coast isn't exactly cheap but even with the cost of shipping it in two boxes (the tubes are packed and shipped separately), it was still half of the low price on eBay.

I'll have to do some "upgrades" to the circuitry that really needs to be done for the amp to run better. I'll also install a few protective circuits to keep the fireworks out of the amp should something going awry.

And...this will force me to run 240 volts out to my shack, something I've been putting off since 2011 when the house was built. I'll be installing a 240v 60 amp sub-panel in the garage in the next month or so.

It'll be nice to have a bit of extra push on my signal when needed. Conditions have been utterly terrible the past few weeks...those DX stations I can hear are not hearing my piss weak little station.

A little blurb on the amp:

Kenwood TL922A Amplifier. Kenwood TL-922A amp

www.universal-radio.com

Real nice a true boat anchor but nice.

 

[timbo]

I think I've collected about all the mod circuits for this amp in the past few weeks. I have a step start PCB which I need to populate and install, another PCB with soft key, LED replacements for the front grain of wheat lamps, bias circuit, and a few other gems, all on one PCB. I just got all the parts for the PCBs today from Mouser Electronics. Also replacing the T/R switch with a vacuum relay. I'm also going hard ground all the grids together. This helps stabilize the amp and as a bonus will get you a few hundred extra peak watts on SSB...

I also installed a 240v 60 amp sub panel in my shop a couple of weekends ago so I could finally have 240vac in there. For the past 9 years I've been running everything in my shop on one 20 amp circuit. Now I have eight 20 amp circuits plus the 240v 30 amp drop for the TL-922. It was nice when I had to use my heat gun this past Sunday to shrink some heatshrink and my shop lights didn't dim when I switched it on...and it ran a lot faster. I don't know what the line voltage dropped to when I switched it on before...now stays a rock steady 127 volts.

 

[UJay]

@timbo this weekend is the New England QSO Party as well... Get on and activate your county, QRO!
(digging up old thread to bump...)
UJ

 

[timbo]

@timbo this weekend is the New England QSO Party as well... Get on and activate your county, QRO!
(digging up old thread to bump...)
UJ

I have a pretty busy weekend coming up and I won't be ready to go QRO for a few more weeks unfortunately but I will definitely get on for a while each day. Are you going to be operating? If so, give a listen for me. Call is KB1Mickey Mouse.

EDIT...I was thinking about this...I may put it all together tonight and run it stock, but without beating on it, and see if/how it works. If it does work stock, then I know I'm working with a known good piece of equipment, Then I can tear it down in a week or two and install the updates.